Mesh Networking

Table of contents

In a wireless mesh deployment, multiple APs (with or without Ethernet connections) communicate over wireless interfaces to form a single network. This wireless communication between APs is called Mesh Networking. Meraki's mesh networking functionality is automatic, self healing and available on all Access Points.

A detailed article on designing wireless Mesh networks can be found here.

Mesh Network Components

In a mesh network, access points can be in one of two states: Gateway, or Repeater.

Gateways

Gateway access points are connected directly to the wired network, granting it an uplink to the Internet. If a gateway loses its Internet connection, it will look for a nearby gateway and automatically fail over to acting as a repeater, allowing it to continue serving clients.

Meraki determines whether a device should be a repeater or a gateway on boot, when the unit sends out a DHCP request. If it receives a DHCP reply from a device on the wired network, it assumes that it has a valid LAN connection and will become a gateway AP. If a gateway AP is unable to reach the LAN gateway/upstream router, the AP will fail over to repeater mode.

Repeaters

Repeater access points are not directly connected to the wired network, instead relying on wireless mesh links to reach the Internet. As long as the repeater has power and a strong (unobstructed, line-of-sight) wireless connection to another repeater or gateway, it will form a mesh link.

Please note, it is not possible to configure a static IP address for a repeater AP; doing so will automatically designate the device as a gateway instead of a repeater.

Both gateways and repeaters can serve wireless clients. It is possible to have multiple gateways in a mesh network, and repeaters will automatically choose the gateway to which it has the strongest connection.

Meraki Mesh Algorithm

Meraki devices in a mesh network configuration communicate using a proprietary routing protocol designed by Meraki. This protocol is designed specifically for wireless mesh networking, and accounts for several unique characteristics of wireless networks (including variable link quality caused by noise or multi-path interference, as well as the performance impact of routing traffic through multiple hops). This protocol is also designed to provide ease of deployment while maintaining low channel overhead.

Each AP in the Meraki mesh network constantly updates its routing tables with the optimal path to network gateways. If the ideal path changes due to node failure or route metric, traffic will flow via the best known path. Data traffic sent between devices in a Cisco Meraki network is encrypted using the Advanced Encryption Standard (AES) algorithm.

Because certain mesh gateways may be located on different IP subnets, each TCP flow is mapped to a particular mesh gateway to avoid breaking established connections. In the event of a mesh gateway failure or the emergence of a new mesh gateway with a better routing metric, all new traffic flows will be routed to the new mesh gateway. The current route to a given mesh gateway may change over time, to adapt to network conditions.

Monitoring Mesh

Mesh monitoring tools are located at the bottom of every AP detail page, which can be accessed by navigating to Wireless > Monitor > Access Points, then clicking on a Access Point.

The image below shows an example AP acting as a repeater. The time selector at the top right hand corner will adjust the timeframe of all of the UI components in the mesh monitoring section of the UI.

The time selector may select data from:

12 Hours

1 day

2 days

1 week

The data is historically visible and can be accessed by panning the information back by increments of 1 week or 1 day. In this case, the UI is showing data for the last two days:

Routes

The Routes Table shows the routes used by different flows over time. As new routes are selected, they are added to the routes table. The overall amount of traffic per-route over the time period selected is shown in the Usage column. The Metric is also displayed in this table, representing a combination of loss and packet delivery times.

Mesh Neighbors

The Mesh Neighbors table shows the APs that have been discovered automatically. The table is typically broken into two sections, "Strong mesh neighbors" and "Mesh neighbors". The Strong Mesh neighbors table lists the preferred APs that may be used for potential routes in the future. The link quality is a metric that takes into account signal strength and packet delivery success rates in each direction. A link quality of 70% or higher is recommended for a strong link.

Wireless Mesh Throughput

Wireless repeaters periodically run a download throughput test to their gateway access point to measure wireless link health. The results are displayed on the the Wireless mesh throughput graph on the right hand side of the page.